Refrigeration systems are used in air conditioners, dehumidifiers, refrigerators, freezers and the like, including commercial coolers, meat lockers, cold rooms, walk-in freezers and walk-in refrigerators. Typical refrigeration systems pass air over fluid- or gas-filled coils, typically with the aid of a fan. A desired refrigeration temperature is achieved through the use of a fluid or gas refrigerant that can be delivered through the coils at a desired temperature. A simple cooling system can use water as a refrigerant if it can be delivered at a desired temperature. More sophisticated refrigeration systems use chlorofluorocarbons (e.g., Freon), environmentally friendly hydrofluorocarbons (e.g., R406a and R 134a), or other refrigerants, which are recirculated through a closed circuit. The refrigerant is typically cooled to a desired temperature by a compression/expansion process that uses a mechanical compressor. Heat transfer systems based on similar principles are found in other applications that are well known in the art, such as heat pumps.
When the temperature of a refrigerant passing through a chilled refrigeration system coil (e.g., an evaporator coil) is lower than the dew point of the surrounding air, condensation tends to form on the evaporator coils and must be removed. In small scale refrigeration systems, such as household refrigerators, this can be accomplished through a drip pan that collects the condensate (i.e., water) and is either manually emptied or evaporated. However, in larger applications, such as commercial refrigerators, freezers and air conditioning systems, the condensation must be drained away from the coils and is usually emptied into a municipal waste or sewer line.
Drain lines that empty into a sewer system typically employ traps to maintain a barrier between occupied spaces and the sewer, so that sewer gases containing sulfuric acid, methane, and other noxious vapors having unpleasant odors, do not back up into the occupied space. Various styles of traps that prevent the escape of sewer gas through a drain have been available since the beginnings of indoor plumbing. P and S style traps have most commonly been used during the last century. These traps rely on fluid (e.g. waste water) flowing through a generally U-shaped length of drain pipe. Due to the force of gravity, a column of fluid is retained in the U of the trap when fluid flow is stopped, thereby creating a barrier to back up of sewer gas. However, in periods of infrequent use, the fluid may evaporate from such traps, allowing gas to enter an occupied space. In a household environment, a homeowner may need to run the faucet in an infrequently used sink or bathtub occasionally, in order to maintain a fluid barrier in the trap and prevent foul-smelling gas from entering the home.
Gas traps can also be used in connection with refrigeration systems, particularly when the system is large and/or enclosed in an occupied or interior utility space. During periods of dry weather or when the system is not in seasonal use (i.e., air conditioning units that are not used in cooler weather), the fluid in such traps can dry out, thereby permitting back-up of sewer gas. Unlike residential plumbing drains, however, refrigeration drains may not be easily accessible for manual refilling. Indeed, such drains may be enclosed in walls or in hard-to-reach areas. Furthermore, a water source, such as a water supply line, is not usually installed in connection with a refrigeration drain trap, making refilling of the trap inconvenient if not impossible.
Moreover, the condensation produced by a refrigeration system is a relatively pure source of fresh water, much like rain water. The availability of sources of pure, fresh water are dwindling in many areas of the world as populations expand in areas where fresh water supplies are limited. In some areas, efforts to conserve water are necessary. For example, many housing developments and municipalities in Southern California have installed systems to recover rain and irrigation run-off, which can be recycled or partially purified for use e.g., in landscape irrigation. Such recaptured and recycled water utilization is estimated to save millions of gallons of water a year that would otherwise need to be imported from other regions of the country.
Refrigeration condensation could provide an additional source of fresh water in water-restricted areas of the world if there were an efficient way to capture it. Even in areas where the availability of fresh water is not a problem, collection and recapture of refrigeration condensation could lessen the burden on sewage treatment systems and municipal water purification systems, while increasing the efficiency of refrigeration systems generating condensation.